I work with 10mm Chinese Hobotai silk and use water based pigment silk paints. This gives the painting a finish which is rich in colour and texture, as well the painting is lightfast and water resistant. For framing purposes, I recommend mounting the silk onto an acid  free white foamboard. The silk is attached to the board by  dry mounting the unpainted white silk border of the painting to the foamboard. The stretched silk is then framed behind glass like you would do when framing a watercolour on cotton rag behind glass. Another method is to sandwich the silk painting between two sheets of museum plexi-glass so that the framed  piece can be seen from both sides much like stained glass.